Permafrost is soil permanently frozen rock and debris, with temperatures below 0 °C throughout the year. Permafrost may contain ice but not necessarily.
Permafrost is located under a thawing layer, which shows positive and negative temperatures during the change of the seasons. It is neither visible nor measurable directly on the ground surface. It exists hidden in entire peak areas. Permafrost is known mainly in connection with its warming and the possible consequences such as increased rock falls and debris flows.
In Switzerland, around 5% of the area contain permafrost, which corresponds to twice of the glaciated area.